McCarthy was struck in the head by a line drive during the 2012 season when he pitched for Oakland, and anxious moments followed. He almost certainly needed surgery to survive and, even then, it was dicey for a while. McCarthy's incident was part of a spate of head injuries to pitchers who were struck with batted balls, and it prompted MLB and the players union to seek safety improvements. Caps manufactured by a 4Licensing Corporation subsidiary called isoBlox are the result. For now.

McCarthy has been skeptical for a while about the technology not being ready, and he told ESPN the caps have several issues that will prevent him, along with most other players, he believes, from using them:

• The cap is too big. Not unlike early models of the oversized batting helmets that have been adopted, the cap just "doesn't pass the eye test," McCarthy says.

• Padding on the inside of the cap makes it too hot and "itchy," even in optimally cool conditions, McCarthy says.

• The cap doesn't fit as snuggly as traditional caps. It's noticeable, even distracting, when a player wearing it moves his head.

Another problem, which wasn't addressed in the ESPN story, is that McCarthy was hit below the cap line. The cap, as constructed, wouldn't have helped him. MLB isn't, at this time, pursuing a design that would extend the cap lower over the head and neck.

McCarthy says nobody wants a safer cap to work more than he does. This cap probably will be safer (so might a batting helmet) but it's not practical enough to use, in his opinion. Via the New York Times, the manufacturer differs:

“The way I look at it is, nobody wanted to wear a helmet in hockey,” said Bruce Foster, the chief executive of 4Licensing Corporation, the parent company of isoBlox. “Nobody wanted the face mask in football. And then you saw the visors and that whole migration.

“I think it’s going to evolve. It’s going to take some time. It’s not overnight. It’s a lifestyle change. It looks different now. It’ll look different until it doesn’t look different anymore.”